Can I run SIP/VoIP over Broadband?

Like most businesses, you may be worried about call quality when moving your phones lines from traditional lines such as ISDN and it is absolutely something that you should think about when planning your migration. However, this should only be one of the service criteria you need to consider when it comes to the internet connection your calls will be routing over.

As you know, there are various types of internet connection, from standard ADSL to Fibre Broadband, through to Ethernet over copper and Ethernet over Fibre.

The key with these products is upload speed, as this will always be slower than the download. Each call takes approximately 0.1Mb of bandwidth, so if you want 10 calls you need a minimum of 1Mb upload speed.

The majority of telecoms providers have advised against using Broadband to run your SIP/VoIP calls due to the product not being able to guarantee download and upload speeds. This greatly depends on the distance you are from the exchange and, in the case of Fibre, the cabinet. Most ADSL services have a maximum upload speed of 1Mb, therefore this service is only really applicable for small offices. You will also need to add Quality of Service (QoS) if available from your broadband provider to ensure your SIP traffic is given priority. Fibre Broadband is much quicker and would allow many more calls due to download speeds up to 20 Mbps, but again I would recommend adding QoS if available.

If you are looking at a broadband service to run your SIP my biggest recommendation would be to upgrade the care level to the highest available. The standard SLA for broadband repair is 5 days Monday to Friday but can be upgraded to 7 or 8 hour fix 24/7 365 depending on your provider. This is considerably cheaper than ISDN care level 4 which has a 6 hour 24/7 365 SLA.

When choosing your ISP you need to look for the following to ensure they only carry business traffic and if possible have an uncontended network, contention on their network could cause latency or jitter which will affect your call quality.

I would also recommend that the network you choose has a peering agreement with your SIP provider of choice if they don’t provide both services. This will ensure that none of your voice traffic needs to go over the public internet.

Overall the benefits of SIP and the cost efficiencies you can achieve using a broadband service makes this a compelling cost saving for the small branch office or small business.

What to consider:

  • Check with your system maintainer that you have the correct equipment to run SIP
  • Remember each SIP call needs around 100Kb upload so your broadband upload and download speeds need to be able to handle the maximum concurrent calls that your business may require (10 calls = 1Mb)
  • Ensure your ISP only carries business traffic
  • Ensure your ISP has a peering agreement with your SIP provider
  • Add QoS to your Broadband connection
  • Pay for the highest care level available

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